Press



March 9, 1937. F. s. CARVER PRESS Filed Jan. 16, 1934 v 5 Sheets-Sheet 1 INVENTOR F red 5. Carl/ er ATTORNEYS PRESS 3 Sheets-Sheet 2 x R m Z x m a WWW m BY M GM-L. flu ATTORNEYS March 9, 1937. F. s. CARVER Filed Jan. 16, 1934 March 9, 1937. F. s. CARVER 2,072,942

PRESS Filed Jan. 16, 1934 3 Sheets-Sheet 5 'INVENTOR Fred ,5. Carver ATTORNEY5 Patented Mar. 9, 1937 UNITED STATES PATENT OFFICE 19 Claims.

My invention relates to presses for separating liquid constituents such as oil or water, from the solid constituents of materials of various kinds, such as cocoa, copra, sewage, etc. which are in, or have preliminarily been reduced to, substantially semi-liquid state and are thus adapted to be moved and put under pressure by a pumping operation.

With the press of my invention, feeding is performed by pumping in the material in a more or less fluid state under pressure, the pumping pressure being relatively high, as' 500 pounds per square inch, for example, and continued for some time after the press has been filled in order to cause an initial filtering; the press chambers are shortened by application of external pressure. whereby a further expressing of liquid is performed, together with caking of residual solids; and further steps of operation include collecting the expressed liquid; elongating the press chambers to their original length; opening up the press chambers in such a way that the press cakes fall out from the opened chambers of the preferably horizontally arranged press; removing the press cakes; re-closing the press chamber sides whereupon the press is ready for refeeding; and repeating these steps throughout further cycles of operation.

It is an object of this invention to provide an apparatus adapted to separate fluids from solids simply, eificiently, rapidly, and substantially continuously, and operation whereof can be as near fully automatic as in practice is feasible. It is a particular object of this invention to provide an apparatus in which the stripping of the residual cakes after pressing will be automatic and certain, doing away with the troublesome hand labor of prying the residual cakes loose after pressing.

A further object consists in provision alternately of platens with a piston and a permanently attached, self-clearing filter plate on one side, and a like filter plate on the opposite side, and of rings adapted to be alternately partly telesct-ped about the filter plate on the piston while also telescoped about the filter plate on the adjacent platen whereby to form a closed chamber within the ring between the filter plates, and to be withdrawn from about the last named filter plate and completely telescoped about the piston, whereby to open up the chamber space about the sides thereof, whereupon the contents may be discharged.

A further object consists in the provision of means whereby all the chamber rings are si multaneously retracted to telescope about the platen pistons, thereby simultaneously opening up all the press chambers at the sides thereof, and after the press cakes have been discharged, all the chamber rings are simultaneously returned to closed press chamber position.

Further objects will appear in the course of the following description:

In the drawings,

Fig. l is a. plan view, with of the press as a whole;

Fig. 2 is a side elevation, with parts broken away, of the press just after it has been fed;

Fig. 3 is a side elevation, with parts broken away, of the press just after the chambers have been shortened and the material compressed;

Fig. 4 is a side elevation, with parts broken away, of the press just after the platens have returned to open position and the chamber forming rings have been moved to open the chamber sides and allow the cakes to fall out;

Fig. 5 is a slightly enlarged cross-section on line 5-5 of Fig. 1 (section through a chamber forming ring);

Fig. 6 is a crosssection on line 66 of Fig. 1;

Fig. 7 is an enlarged cross-section of the chamber ring and filter plates in position for feeding, and takenon line 1-1 of Fig. 5;

Fig. 8 is an enlarged detail section of the springs between the platens and the chamber rings, taken on line 8-8 of Fig. 5; and

Fig. 9 is an enlarged sectional detailed view of the chamber ring retracting means on line 9--9 of Fig. 4.

The press is horizontally supported on standards I 0, and comprises a ram head I2, a resistance head l4, and strain rods l6 connecting the heads and fastened thereto by nuts l8. Strain rods ii are square except near their ends, where they are of reduced circular section, so that the heads 12 and I4 abut against the shoulders of the rods and so are held solidly. There are preferably four of the strain rods 16, arranged in upper and lower pairs, transverse sections (Figs. 5 and 6) showing one of rods H3 at each corner.

Extending between the heads l2 and I4 and secured thereto, and preferably'supported upon the lowermost pair of strain rods I 6' are two slide-way members 20. A series of platens 22 ride on these slide-way members 20, being shaped 50 as at 24 to extend over and ride upon same (see Fig. 6). The sides of the platens 22 are cut away at 26 to clear rods which are described hereinafter. In the particular embodiment illustrated, there are eleven of the platens 22, with ten press 55 parts broken away, 10

chambers 23 between them, the side walls of said press chambers 23 being provided by the chamber rings I2, hereinafter described. The material to be treated enters the press chambers through the radial and central passages and 22 in said platens 22., Thus the last entering and relatively softest portion of the caked material in the chamher is at the axis of the chamber. This avoids any tendency of the press platens being skewed or wedged out of line and the press structure twisted or buckled by uneven resistance encountered when high pressures are applied.

Movement of platens 22 toward the right is stopped by means of stepped stop plates 26, which are preferably secured to the inner faces of the strain rods I6, and are provided with as many stop abutments 36 as there are movable platens, said stops 36 being equally spaced and stepped up successively toward the ram end of the press. The platens 22 are provided with abutments 32 :at successive levels, so that each of the platens 22 is limited in its press-chamber-elongating movement (to the right) by engagement of abutment 32 thereof with one of stop abutments 36.

.These stops 36, 32, while serving to limit movement of platens 22 to the right so as to leave same in evenly spaced positions, do not interfere in any way with the movement of said platens to the left whereby the press chambers are shortened and material in the press chambers is compressed. In the embodiment shown there are four stops 36, and four abutments 32, for each platen 22, one at each corner, whereby the platens 22 in their stopped positions are parallel to each other and in planes perpendicular to their line of movement.

Each platen 22 (except the one on the lefthand end) has secured on its left face a piston 34, provided with a permanently connected filter plate 36, and each platen 22 (except the one on the right hand end of the press) has secured on its opposite or right face a second permanently connected filter plate 36', all of these parts, namely platen 22, piston 34, filter plate 36 on face of piston 34, and filter plate 36 on the opposite side of the platen 22, moving together as a platen unit. Filter plates 36 and 36 are preferably made self-clearing by progressive enlargement outwardly of successive holes and passages, in accordance with my U. S. Patent No. 1,771,526, dated July 29, 1930, and remain permanently in place on piston and platen. The preferred form of filter plate is shown in detail in Fig. '1.

This filter plate may consist of a fine filter cloth 38, backed with a foraminated metal sheet 46, which is in turn backed with coarse, preferably flattened, wire mesh 42, said parts 38, 46 and 42 being received in a recess 44 in a backing plate 46, having circular slots 48 in the face next to mesh 42 and outwardly enlarged passages 56 communicating with radial slots 62 through which the expressed fluid is conducted to discharge slots 54 in the lower surfaces of pistons 34 and discharge slots 66 in the lower left side of rings 12. The filter plate 36 is secured to piston 34 and the filter plate 36' is secured to platen 22, as by means of screws 66 passing through the backing plate 46. A preferably beveled ring 68 screwfastened to backing plate 46 holds the filter cloth 38 and backing members 46, 42 in place in recess 44. The backing plate 46 of filter plate 36 has an annular groove 66 recessed from the periphery and from the side nearest the chamber, in which a packing ring 62 of felt or the like is fitted and clamped in place by ring 66. A packing of felt in this combinationis peculiarly advantageous in that some material filters through it, building up a seal of residual solids.

In filter plate 36', which is mounted on the platen 22, screw-threaded plug 64' having a thin beveled-off flange head 68' holds the assembled filter screens centrally to backing plate 46.

In filter plate 36, which is mounted on the piston 34, a similar plug 64 with head 66 fastens the screens. This plug has a bore 66 which communicates through axial bore 22' of piston 34 with radial bore 22 of platen 22. Bore 66 in plug 64 contains a spring seated check valve 63 whose surface is flush with the plug head 66 and therefore substantially fiush with the chamber wall as a whole.

Semi-liquid material to be filtered is pumped from a supply source through common pipe line 16, from which individual flexible or universally jointed pipes ll connect with the several bores 22' in platens 22. When material is pumped in, it enters the press chambers individually and substantially equally. The check valves allow it to enter, but close when the chambers are completely filled and the pressure of the feeding is not greater than the pressure inside the chamber.

Rings 12 form the outer walls of .the press chambers 23. The chamber rings 12 have side lugs 14 with surfaces I6 riding on the same slideway members 26 on which the platens 22 are guided and whereby chamber-rings 12 are slidably supported (see Fig. These chamber-rings are of an inner diameter to fit closely over the pistons 34 and filter plates 36, 36'. Their inner edges are beveled for easy entrance as at 18, 86. Chamber-rings 12 are axially slidable' with respect to the pistons and filter plates. When the platens 22 are spread apart against stops 36, and the chamber rings I2 are thrust away from the platens 22 by springs 88, referred to below, the chamberrings I2 overlap both the filter plates 36 and 36, and provide the chambers 23 within the chamberrings 12 and between said filter plates. The combined thickness of each piston 34 and its filter plate 36 is equal to or greater than the thickness of the corresponding rings 12. Thus the rings 12 in the first named position can close the sides of the press chambers 23, or they can be retracted into another position telescoped over the pistons 34 and filter plates 36 so as to open the sides of the chambers.

The chamber rings 12 telescope about pistons 34 and there is a lost motion spring connection between each ring I2 and the platen 22 to the right thereof to which the piston 34 is secured. Said rings 12 are normally held away from platens 22, that is, to the left as seen in Fig. 2, by compression springs 88 interposed between ring 12 and platen 22 to urge each ring 12 to the left away from the associated platen 22 next to its right. The springs 88 are mounted in such a way that they may telescope into the ring 12 and/or the platen 22, permitting the piston 34 to be completely telescoped by ring I2, and ring 12 to be brought into direct contact with platen 22 by application of suitable pressure. Even if rings 12 are not brought all the way over to platens 22, this telescoping arrangement makes the pressure of the springs more nearly uniform in all positions of the rings. As shown, springs 88 are received at one end in slight depressions 36 in the platens 22, and at the other end in deep annular grooves 32 in lugs 34 extending out from the rings 12. Bolts 66 connect and adlustably limit platen on its right just into contact with the platen on its left, with a fraction of an inch to .spare (see Fig. 8). Pins 96a, such as cotter pins, are then inserted through holes in bolts 96 and their nuts 96!), to lock same at the desired adjustment.

A hydraulic main ram I04 is provided in the head I2 for actuating the platens 22 and pistons 34 and thereby shortening each of the press chambers 23. Ram I04 bears on the right hand end platen 22, through the intermediacy of cross head I06, which is bolted to the ram and by its lugs I08 rides on slideway members 20 and sosupports the end of the ram when projected (see Fig. 6). The head I2 has a hydraulic cylinder IIO therein, in which the ram I04 operates. A suitable packing joint is provided, having a U-shaped packingring H2. The inner end of the ram I04 is preferably cut out as at II4 both to save weight and to leave room for a secondary hydraulic chamber to be later described. A fluid connection II6 from a pressure source, with suitable control valving, communicates with chamber IIO.

When fluid under pressure enters at II 6, ram I04 moves to the left, shortening each of the press chambers by the platen pistons 34 telescoping in the chamber rings I2. Material in the chambers is thus compressed.

The material supplied under pressure to the press chambers past the check valves 69 is prevented by said valves from flowing backwardly. The oils and other liquid constituents pass out through the filter plates and run through the channels into a pan I20 which is provided below the press to catch them, leaving the solids in the press chambers 23 in the form of a hard cake I2I. Pan I 20 is horizontal pivoted along one side as at I22, to permit it to swing down out of the way. On the opposite side a flange I24 extends inwardly to prevent dripping when the pan is in down position. A spout I26 on the same side of pan I 20 as the pivot I22, and pointing away from flange I24, drains the contents of the pan into a tank or other receiver I28.

When the pressing is complete, the platens 22 with pistons 34 are retracted to the right by ex- .pansion of springs 88 upon pressure being released in the ram, each ring I2 remaining stationary relative to its press chamber as the pistons 34 telescope backwardly in said rings and the chambers 23 are elongated by retreat of pistons 34 therein, said chambers 23 being empty except for cake I2I, which is freed from filter plate 36 upon platen 22 retreating and thereby withdrawing plate 36, but cake I2I remaining engaged with the inner wall of ring I2 and with fllter plate 36' of the next platen to the left.

The rings I2 are then retracted to the right. As they first move away from fllter plates 36 the cakes move with the rings and are pulled free of filter plates 36. As the rings continue to move to the right they telescope completely over pistons 34, which thereby expel the cakes from,

the rings. The cakes then drop out, the press chambers having been opened about their sides due to the retraction of the rings over the pistons.

Mechanism is provided for retracting the rings I2 to open up chambers 23, as follows: Rods I30, preferably two in number, one on each side of the press, are mounted to slide longitudinally of the press. The resistance head I4 is provided with lugs I32 extending out to the sides and having fixedtherein bushings I34 in which rods I30 are slidable. These lugs I32 have cam grooves I36 cut through from bushings I34, in which are guided the coacting pins I38 on rods I30. When rods I30 are moved longitudinally, these pins and cam groove parts I36a. first rotate rods I30, after which rods I30 move on longitudinally in parts I 36b of the grooves I36 without further rotation.

The rods I30 are slidable in bores I40 in lugs I42 of rings 12. These bores I40 are slightly larger than rods I 30, and have cut-outs I44 at their opposite sides. Pins I46 extend through rods I 30 and project therebeyond. These pins I46 are so disposed with respect to the bores I40 in the rings I2 that when the rods I30 are at the leftmost end of their paths the pins I46 and cut-outs I 44 coincide, and the rings I2 can pass freely over them, along the rods I30. When the rods I 30 move to the right they rotate due to the camming action of groove-portions I360; to bring the pins 146 out of coincidence with the cut-outs I44, so that the rings I2 are engaged by pins I46 and must move to the right with the rods. Each rod I30 is provided with a pin I46 for each ring I2, so spaced that when the rods I 30 are moved all the way to the right, the rings 12 are all retracted to open the press chambers. The portions containing cut-outs I44 may be replaceable bushings as indicated at I44a to take care of wear.

Sliding movement is imparted to the rods I30 by means of a secondary hydraulic ram-andcylinder I48 in the head I-2 having a ram I55) and cylinder I5I. Suitable packing glands I52 are provided, and fluid under pressure is introduced, by suitable valving, through pipe connection I54. The rods I30 are constrained to move longitudinally with the yoke, but are free to rotate with respect thereto. This is provided for by having each of .the rods reduced to a smaller diameter I58 at its outer end, on which small-diameter part is slipped first a washer I60 and then the yoke I56, which has a circular bore I62 large enough to give a clearance about part I58. The rod is then again stepped down and threaded, and a smaller washer I64 and a nut I66 put on it. Thus it is possible to make the nut tight without clamping the yoke tightly.

At the other side of the head I2 a pin I61 through each rod I30 holds a washer I68, and a compression spring I12 is provided around the rod I30 between washer I68 and the head I2. These springs return the rods I30 to the left when the fluid pressure in chamber I48 is released, permitting rings I2 to be projected by springs 88 to the extent permitted by bolts 96, engaging the next platen 22 to the left.

Operattion ing over fllter plates 36' on the next adjacent platen 22 to the left. Material to be treated is pumped into the chambers 23 under pressure, and this pressure is great enough to cause a considerable initial filtering of the material, thereby increasing the quantity of material treated at each pressing and producing a thickening of the residual material in the press chambers, and increasing the thickness of the final cake (see Fig. 2).

Then hydraulic pressure is applied to the main ram, which forces pistons 34 into the press chambers, thereby shortening the press chambers, and compressing the material and further expressing the liquids through the filter plates (see Fig. 3). The expressed liquid is caught by the pan below the press and led off.

Before hydraulic pressure is released on the main ram, pressure is released from the feed line and is not again restored until the press is ready for the next filling.

Hydraulic pressure being released from the main ram, the springs 88 return the press platens, pistons and filter plates conjointly to expanded position and return the main ram piston.

Each chamber ring 12 has not up to now moved relative to the platen 22 at its left. The compressed cake l2i is freed from filter plate 36 and remains at the left side of the press chamber 23, the filter plate 36 on the platen piston 34 at the right of the cake l2l having moved within the chamber ring 12 away from the cake l2| when the platens were retracted.

The valve to the secondary hydraulic ram is now opened, and the rods I38 move to the right, rotating as they start to move, so that the pins I46 catch the rings 12 and pull them to the right over the pistons 34, compressing springs 88 and opening the sides of press chambers.

The compressed cake l2l, which in formation was severely pressed within the ring 12 and is held thereby, is stripped from the filter plate 38' and moves to the right with the ring 12. How-.

ever, movement of the cake to the right is stopped by the plate 38 of piston 34, and as the movement to the right of ring I2 continues and ring 12 becomes completely telescoped over the platen piston 34, the cake l2| is pushed out of chamber ring 12 by piston 34 and falls free. (SeeFig. 4.)

At some point of time between the end of the pressing stroke of the main ram and the falling of the cakes, the oil-receiving pan is tilted away, and a device to catch the cakes substituted or exposed. Such device may take the form of a movable rack, or a conveyor I82 under the oil pan, as shown in Fig. 2.

After the cakes have dropped out, the pressure on the secondary ram is released and the chamber rings 12 are allowed to move to the left under the influence of springs 88, thereby reclosing or providing side walls anew for the press chambers, and the rods I30 are allowed to be moved back to the left by springs I12, and such operation is repeatedas long as desired.

At some point of time between the discharging of the cakes and the pumping in of a new feed batch, the oil-receiving pan is returned to operative position.

The platens and pistons may be heated as by steam if desired, and for illustration I have shown steam pipes I88 and circulation passages I92 in the platens 22.

It will be seen that the entire operation is practically completely automatic, and can be repeated indefinitely, with no need for attention except manipulation of a few control valves. 'fhere is no need for any hand loading, stripping cakes off by hand, or attaching and removing of parts during the operation, as there generally is in expressing presses. The present machine turns out a much greater production in a given length of time, and does so with much less work and 5 difliculties on the part of. attendants, since it is almost wholly automatic and continuous in operation. It will be obvious that with the press here disclosed it would be perfectly possible and a relatively simple matter to connect up a valve control to operate the press entirely automatically.

While I have described a particular preferred embodiment of my invention, it will be understood that it is not limited to the particular showing herein, but may be varied and modified within the scope of the appended claims.

I claim:

1. 'In an expressing press having a horizontally disposed series of co-axial press chambers, coaxial filter plates relatively movable axially forming the end walls of said chambers, a ring for each chamber forming the side walls thereof, each of said rings normally lapping over a filter plate on each end of its press chamber to enclose the press chambers, means for feeding material, which is to be pressed individually into the individual chambers while the filter plates are in expanded relation and the rings are in chamber-forming position, means for moving the filter plates axially toward each other under pressure, means for leading off expressed fluids, means for conjointly returning the filter plates to expanded relation with one set thereof remaining in unchanged relation to said rings and the second set thereof moved away from the first set within said rings, and means for sliding said rings relatively to the second set of filter plates to telescope thereover and cause the cakes in the chambers to be pushed out and dropped.

2. In a filter-hydraulic press, a plurality of press chambers, and an individual feed from without the chambers to the axial center of each press chamber. 3. In a filter-hydraulic press, a plurality of press chambers, and an individual branch line feed from a common manifold to the axial center of each press chamber.

4. In a filter-hydraulic press, a plurality of press chambers, an individual branch line feed from a common manifold to the axial center of each press chamber, and a check valve in each branch feed line flush with the press chamber wall.

5. In a filter press, a series of axially aligned platens with pistons thereon, rings each co-acting with a piston and the next platen of the series to form a press chamber, filter means in the press chambers, and means for leading forced material to be treated laterally in through each platen, and then through its piston centrally into the adjacent press chamber alone.

6. In a press, longitudinally movable chamberforming rings and intermediate platens mounting lel coaxial filter plates and a ring fitting around the filter plates and being telescopableover one of the filter plates, said plates and ring defining a press chamber, means for moving one of the filter plates toward or away from the other, means for keeping the ring stationary relative to one of said filter plates as they start to separate while permitting the second filter plate to move relatively to the ring, an individual feed entrance from outside the press chamber provided to communicate with the chamber through said second filter plate, a check valve seat at substantially the mouth of the feed entrance and facing toward the press chamber, and a check valve cooperating with said valve seat, the head of said valve when closed forming a portion of the continuous press chamber wall.

8. In a press, a series of co-axial platen units relatively movable longitudinally, rings surrounding the spaces between said units to form press chambers, control rods for said rings movable to two positions, in the first of which the rings are free of the rods to move as the platen units move, and upon movement to the second of which the control rods move the rings withthem.

9. In a press, a series of filter plates, rings around pairs of adjacent filter plates, means for moving one filter plate of each pair within the ring toward the other, means for re-spreading the filter plates, means for completely telescoping the rings each over one filter plate of a pair, said last named means comprising a member mounted on the press to move in a definite path, in one part of which path it does not afiect movement of said rings, and in another part of which path it effects said telescoping of said rings each over one filter plate of a pair.

10. The device of claim 9 in which each of said rings has a passage with a channel communicating with the passage, and the means for completely telescoping the rings over one filter plate of a pair comprises a rod extending through said passage and having a protuberance thereon which can freely ride through said channel when made to angularly coincide therewith.

11. In a press, a series of filter plates, rings around pairs of adjacent filter plates, means for moving one filter plate of each pair within the ring toward the other, means for re-spreading the filter plates, means for completely telescoping the rings each over one filter plate of a pair, said last named means comprising a member rotatably and slidably mounted on the press, passages for said member through said rings with openings extending from said passages, protuberances on said member in the neighborhood where the member extends through the passages in the rings, and cam means associated with the mounting of the slidable member on the press adapted to either bring the protuberances into engagement with the openings, thereby permitting the rings to be freely moved,or to bring the protuberances into engagement with the rings and out of register with the openings, thereby enabling the slidable member to move the rings into position to telescope over one filter plate of a pair.

12. In a filter press, a series of platen units each comprising a platen with a lateral inlet, a piston and a filter plate on one side of the platen and a conduit therethrough for material to be treated, and a filter plate on the opposite side of the platen, a series of straight-through-bore 75 rings between said platens and adapted to surround said pistons and filter plates, springs between that side of each platen which bears a piston and the adjacent ring for thrusting said platen and ring apart and causing the ring to fit about the last named filter plate on the next platen of the series, and means for limiting the separating relative movement of said platen and ring.

13. In a press, a plurality of co-axial units each comprising a platen, a filter plate secured to one side thereof, a piston secured to the other side thereof and a filter plate secured to said piston, rings, whose internal diameters are throughout as large as the filter plates, mounted on the pistons and surrounding facing filter plates of adjacent units and overlapping same, said rings being telescopable over the pistons they are mounted on, compression spring means between each ring and the platen to which is attached the piston over which that ring telescopes, means for limiting the spreading action of said spring means, and means for limiting the movement of each platen in the direction in which said spring means urges it.

14. In a press, a horizontal series of co-axial platens, each platen having secured on one side a filter plate and secured on the other side a piston having a. filter plate secured on its outer face, rings between adjacent platens fitting over the adjacent spaced apart filter plates to form press chambers, each ring being telescopable over the adjacent piston and its filter plate, individual conduits leading from the edge portions of the platens through the pistons and into the chambers individually, check valves in said conduits, means for pressing the platen units closer together to shorten the press chambers, compression springs interposed between each ring and the adjacent platen which bears the piston over which the ring telescopes, ring actuating devices so mounted as not to interfere with movement of the rings until themselves actuated, and so arranged that when actuated they urge each ring in a direction to telescope it over the adjacent piston and compress the springs bearing against the ring, spring means urging said ring actuating devices to position where they do not interfere with movement of the rings, and a series of stops which keep the platens from moving with the rings.

15. In a filter press, a series of axially aligned platens with pistons thereon, rings each coacting with a piston and the next platen of the series to form a press chamber, press chambers, and means for leading forced material to be treated in through each platen and then out therefrom centrally into one adjacent press chamber only.

16. In a press, longitudinally movable chamberforming rings and intermediate platens with pistons and permanently attached front and back filter plates, the rings each fitting about a front and an adjacent back filter plate, means for leading pumped semi-liquid material into the respective platens andthence laterally into the respective individual chambers, means for shortening and then expanding the pressure chambers, and means for mechanically effecting simultaneous retraction of a plurality of rings over a plurality of pistons whereby the residual cakes in such rings are automatically gravitationally discharged.

17. A press comprising three or more axially aligned expressing chambers, a power device for axially contracting all the chambers simultaneously to express fluid therefrom, and feed lines communicating from without the chambers to the several chambers individually at their axial centers.

18. In a combined filter press and hydraulic press. a series of piston-like filter platens arranged to be pushed together by a hydraulic ram in one and the same direction, the filter platens having filter surfaces on both sides and having inlet passages for material to be filtered, and

chamber rings disposed about the filter plate and for returning the same plurality of the rings substantially simultaneously to close the corresponding chambers without need for resort to intermediate manual manipulation with respect to fewer rings than the said plurality thereof.

19. In a combined filter press and hydraulic press, a series of piston-like filter platens arranged to be pushed together by a hydraulic ram in one and the same direction, the filter platens having filter surfaces on both sides and havins inlet passages for material ,to be filtered, and chamber rings disposed about the filter plate pistons and shiftable with respect thereto to form when in closed position. together with the filter surfaces of the platens, filter-and-press chambers, and the rings being shiftable retractibly with respect to their filter platen pistons to open the said chambers, and means for substantially simultaneously retracting all the rings with respect to their platen pistons and thereby D 7- mitting all the cakes to be discharged substantially simultaneously by gravity and for thereafter returning all the rings substantially simultaneously to close all the chambers without need for resort to intermediate manual manipulation with respect to fewer than all the rings.

FRED S. CARVER. 

